1. Field of the Invention
The present invention relates generally to laser retroreflector arrays and, more specifically, to a laser retroreflector array with cat-eye retroreflectors.
2. Description of the Related Art
A laser retroreflector is used to return a laser beam in the direction of its source. The laser retroreflector can therefore be utilized to make precise determinations of distances from the laser retroreflector. For example, an array of laser retroreflectors can be provided on a satellite for the purpose of studying the Earth's crustal dynamics.
A conventional laser retroreflector array (LRA) has used optical cube-corner prisms as retroreflectors. The optical cube-corner prisms have provided reflections from these satellites With precisely known relationships to the satellite center of gravity. For example, the satellites LAGEOS1 and LAGEOS2 both utilize such laser retroreflector arrays with cube-corner prisms. LAGEOS2 is described in "Prelaunch Testing of the Laser Geodynamic Satellite (LAGEOS)" M. W. Fitzmaurice, P. O. Minott, J. B. Abshire, H. E. Rowe.
With the conventional laser retroreflector arrays using cube-corner prisms, however, it is impossible to design the laser retroreflector arrays so that only one cube-corner prism at a time reflects the laser beam. Due to the wide angle of acceptance (approximately 120.degree.) of these conventional cube-corner prisms, it is impossible to design the array so that only one cube-corner prism reflects the laser beam at a time. This causes the laser retroreflector arrays to be affected by coherent interference effects between the cube corners and creates chromatic and polarization effects. Also, range correction is rendered dependent on the position of the receiver in the far-field diffraction pattern. The net result is a limitation on the accuracy of laser ranging measurements, as well as an increase in cost and decrease in efficiency of providing precise laser ranging results.